Correct return codes during racy destruction.

Errors in PnP retun codes found when testing under driver
verifier with mixed VM lifecycle operations. Under some
rare cases, it is possible to get more than one PnP
"remove-like" operation. This results in a PnP remove
operation being processed whilst the device is already
in the deleted state.

This patch fixes the immediate cause of the bugfixes,
by fixing the return code. Device destruction is
unchanged. Investigation into the root cause is still
ongoing.

Signed-off-by: Martin Harvey <martin.harvey@citrix.com>
Cosmetic fixes.

Signed-off-by: Paul Durrant <paul@xen.org>

diff --git a/src/xencons/driver.c b/src/xencons/driver.c
index 5a4d1d3f22a4ce45075770036d30baaca1f694ef..56e27750525906c83b68f0391de227ef5d068a19 100644 (file)
--- a/src/xencons/driver.c
+++ b/src/xencons/driver.c
@@ -194,8 +194,20 @@ Dispatch(
     ASSERT3P(Dx->DeviceObject, ==, DeviceObject);
 
     if (Dx->DevicePnpState == Deleted) {
+        PIO_STACK_LOCATION  StackLocation = IoGetCurrentIrpStackLocation(Irp);
+        UCHAR               MajorFunction = StackLocation->MajorFunction;
+        UCHAR               MinorFunction = StackLocation->MinorFunction;
+
         status = STATUS_NO_SUCH_DEVICE;
 
+        if (MajorFunction == IRP_MJ_PNP) {
+            /* FDO and PDO deletions can block after being marked deleted, but before IoDeleteDevice */
+            if (MinorFunction == IRP_MN_SURPRISE_REMOVAL || MinorFunction == IRP_MN_REMOVE_DEVICE)
+                status = STATUS_SUCCESS;
+
+            ASSERT((MinorFunction != IRP_MN_CANCEL_REMOVE_DEVICE) && (MinorFunction != IRP_MN_CANCEL_STOP_DEVICE));
+        }
+
         Irp->IoStatus.Status = status;
         IoCompleteRequest(Irp, IO_NO_INCREMENT);
         goto done;